My prior U.S. Pat. No. 4,111,249 relates to a basic resilient pneumatic tire which is provided with a band between the crown and the carcass portions of the tire which permit such a tire to be operated at reasonable speeds in a substantially normal manner irrespective of the state of pressurization of the tire. This capability is provided in the tire when pneumatic support is reduced or absent by means of an annular structural compression element which is stabilized by radial reinforcing means. A solid high-strength band fixed in place in the crown of the tire radially inward with respect to the tread can be utilized as the compression element. This band is stabilized by the radial means which behave in a manner similar to individual tensile spokes to provide load supporting strength such that the band is reinforced thereby. The tire of this invention can be completely depressurized and, with a predetermined deflection that will range approximately 30 to 50% of the pressurized condition, it will bear the weight of the vehicle such that it can be driven at reasonable speeds without an appreciable or dangerous degradation in its handling qualities or performance.
In the tires of this type, the annular compression element which reinforces the tire is stabilized by radial elements in the sidewalls of the tires. The radial elements can be one or more plies of radial textile cords or metal wires. Various tire constructins are known in the art that have a casing or carcass comprising one or more plies of weftless cord (or wire) fabric extending from bead to bead wherein the cords in each ply are substantially radial in orientation; i.e., the cords are oriented substantially normal to the beads and the crown centerline of the tire. In a monoply radial tire construction, the casing cords normally have a 90.degree. bias angle; i.e., in the unshaped carcass they extend perpendicular to the planes of the beads. In a two-ply radial tire construction, the cords in each casing ply are usually oriented at oppositely disposed small angles of up to 10.degree. with respect to the perpendicular to the bead planes, in which case the respective body plies are said to have oppositely disposed bias angles of 80.degree. or greater (but less than 90.degree.). In four-ply or heavier radial tire constructions, similar opposed orientation of the cords in successive body plies is usually employed. All of these casing or carcass constructions are contemplated within the scope and meaning of the expressions "radial" and "substantially radial" as used herein.
Therefore, the banded tire of the mentioned patent provides a reinforced pneumatic tire that has the compatibility of use in vehicles of a conventional tire yet which will enable the vehicle with which it is used to be operated safely at reasonable speeds after a blowout or other damage causing a partial or complete loss of pressurization. The tire has a radially stabilized annular reinforcing compression band in which the bending stiffness and centrifugal forces created by the band mass and the stability influence of the radial reinforcing means ensure safety against instability in the event of high-speed blowouts, particularly those occurring with coupled highway vehicles such as trucks and trailers or with aircraft during landing or takeoff runs.
The reinforced pneumatic tire has restrained carcass and tread motion at operational speeds such that the rolling resistance is lower than in conventional radial tires especially at low inflation pressures. A large percentage of the load is carried in the elastic properties of the band reinforcement incorporated therein such that the added restraint to carcass motion (standing wave phenomenon) results in lower tire heating at higher speeds whereby high locomotion efficiency is achieved.
The homogeneous band has an inherent lateral stiffness that furnishes a high resistance to side loads for given foot-print lengths to provide high steering authority such that the margin of safety in operation is increased significantly when compared to conventional tires.
The tire can be operated safely while unpressurized or under partial inflation such that the tire "foot print" is elongated and the "bulldozing" resistance is reduced by the low entry angle into the soil so that superior weak-soil performance is obtained. The design permits a selection to be made from a variety of high-strength materials for use in the band and in which also a choice in the construction materials and dimensions of the band can be made to thereby give a desirable uniform foot-print pressure at a given deflation level such that the weak-soil performance is enhanced.